title: CsB3GeO7 and K2B2Ge3O10: explorations of new second-order nonlinear optical materials in the borogermanate systems.
abstract: Two novel alkali(I) borogermanates with noncentrosymmetric structures, namely, CsB 3GeO 7 and K 2B 2Ge 3O 10, have been synthesized by high-temperature solid-state reactions in a platinum crucible. The structure of CsB 3GeO 7 features a novel three-dimensional (3D) framework composed of cyclic B 3O 7 (5-) groups that are interconnected by Ge(IV) cations, whereas the structure of K 2B 2Ge 3O 10 is a new 3D network based on cap-shaped [Ge 3B 2O 14] (10-) clusters that are interconnected via Ge-O-B bridges. CsB 3GeO 7 exhibits a second-harmonic generation (SHG) response that is about 1.5 times that of KDP (KH 2PO 4), whereas the SHG signal of K 2B 2Ge 3O 10 is very weak. Both compounds are insulators and transparent in the range of 300-5000 nm. The electronic structure calculations for both compounds also have been performed.
authors.affiliation: State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, PR China.
authors.forename: Fang
authors.initials: F
authors.lastname: Kong
authors.forename: Hai-Long
authors.initials: HL
authors.lastname: Jiang
authors.forename: Ting
authors.initials: T
authors.lastname: Hu
authors.forename: Jiang-Gao
authors.initials: JG
authors.lastname: Mao